The inventive concept relates to a memory devices, systems and methods, and more particularly, to command/address calibration.
In a memory system, for example, a dynamic random access memory (DRAM) system, a signal transmitted and received via a bus between a memory controller and a DRAM experiences propagation delays. The propagation delays may be affected by various factors, such as interconnection capacitors or a parasitic capacitances existing on the bus, a substrate, or the like. As a data rate of the DRAM increases, a propagation delay and/or variations of propagation delays degrade signal integrity. It is desirable to find an optimal signal window or compensate for signal skew between signals, such as between data signal and a clock signal, a command signal and a clock signal and/or address signal and a clock signal.